1. Field of the Invention
The present invention generally relates to devices for compacting soil which has been backfilled into ditches during trenching operations for the laying of cable, pipe and the like and, more particularly, to the wheel assemblies utilized with such soil compactor devices. Specifically, the present invention relates to unique wheel assemblies for such devices having improved load bearing systems and wheel locking and attachment mechanisms.
2. Description of the Prior Art
In trenching or ditch digging operations for the laying of underground cable and pipe, the ditches must be backfilled once the cable or pipe has been laid within the excavated ditches. This backfilling operation requires proper compaction of the soil, which compaction is governed by very specific federal and state regulations. In particular, federal regulations, where appropriate, require a minimum of 95% soil compaction compared to the original soil. As a result of such requirements, soil compacting devices have evolved to achieve proper compaction of the backfilled soil within ditches.
Such soil compaction devices usually include one or more wheels which carry compacting members or feet on the circumferential edge thereof. The wheels are mounted about an axle generally for free rotation thereabout. The size of the wheel and the size and shape of the compaction feet will vary depending on the width and depth of the ditch which has been excavated. For example, ditches required for the laying of telephone cable and the like are much narrower and shallower than ditches required for the laying of pipeline. Therefore, the size and shape of the compaction feet will vary according to the end use of the soil compaction device. The assemblies carrying the compacting wheels are generally mounted to a hydraulic arm system which in turn is carried at the rear of a ditch excavating machine. A front loader is utilized to backfill the ditches after excavation and laying of the cable or pipe.
Operation of such devices is quite simple. The hydraulic arm system is utilized to roll the freely rotating wheel assembly within the ditch or ditches longitudinally back and forth, thereby compacting the soil due to the weight of the wheel assembly as well as compressive force exerted by the hydraulic arm system. As backfill soil is compacted, additional soil is then added to the ditch which is in turn compacted. Therefore, each wheel is moved higher and higher within the ditch until it is completely filled and compacted relatively uniformly throughout the ditch's depth. It should be noted that the wheel assembly generally also moves laterally a bit within the ditch as it is moved longitudinally therealong to assist in complete compaction of the soil.
While such soil compaction devices have been very successful in meeting the required compaction regulations and are generally efficient during operation, in that one wheel assembly can generally keep up with an excavator and front end loader, certain problems and difficulties have arisen. For example, the compressive force exerted on the soil by the wheel assembly results in sizeable radial loading forces on the axle of the wheel assembly. Likewise, the forces exerted during lateral movement of the wheel assembly within the ditches create substantial axial forces on the wheel axle. These radial and axial loading forces have previously been carried and absorbed by bearing arrangements which have tended to wear out very quickly. For example, certain prior art designs have incorporated brass bushings to distribute the radial forces and brass thrust bearings to absorb the axial or lateral forces. Such brass bushings and thrust bearings tend to wear out quickly as a result of the nature of the material, the sizeable load forces encountered during such backfill operations, as well as the presence of dirt which passes through seals and lodges in the bushing or bearing itself. Such rapid wear and premature failure of bearing arrangements have caused substantial expense as well as down time for existing soil compactor devices.
Another problem encountered with existing soil compactor devices is that of wheel replacement as well as bearing maintenance. Because of the substantial radial and axial loads imposed on the wheel assemblies of such devices, the wheels themselves have generally been permanently welded onto the axle. Consequently, if a compactor foot or some other portion of the wheel becomes broken thereby requiring replacement of the wheel, or if the bearings within the wheel assembly require replacement or maintenance, substantial time and effort is required to remove the permanently mounted wheel in order to either replace it or to gain access to the bearings. In either event, the fact that the wheel has been permanently welded or otherwise mounted to the wheel assembly requires substantial expense and time in terms of maintenance or replacement of parts. However, attempts to provide removable wheels have previously hereto been unsuccessful in that the wheel mounting mechanisms so used have proven incapable of sustaining the load forces imposed thereon over a prolonged period of time in the environment in which the device is used. Thus, there is a need for a mechanism permitting ready removal and/or replacement of wheel assembly components for such soil compactor devices.